filebuf * open ( const char * s, ios_base::openmode mode );

Open file

Opens a file whose name is s, associating its content with the stream buffer object to perform input/output operations on it. The operations allowed and some operating details depend on parameter mode.

If the object already has a file associated (open), this function fails.

Parameters

s

C-string containg the name of the file to be opened.

mode

Flags describing the requested i/o mode for the file. This is an object of type ios_base::openmode. It consists of a combination of the following member constants:

flag value	opening mode
app	(append) Set the stream's position indicator to the end of the stream before each output operation.
ate	(at end) Set the stream's position indicator to the end of the stream on opening.
binary	(binary) Consider stream as binary rather than text.
in	(input) Allow input operations on the stream.
out	(output) Allow output operations on the stream.
trunc	(truncate) Any current content is discarded, assuming a length of zero on opening.

Return Value

Example

// filebuf::open ()
#include <iostream>
#include <fstream>
using namespace std;

int main () {

  ifstream is;
  filebuf * fb;

  fb = is.rdbuf();
  fb->open ("test.txt",ios::in);

  // >> file buffer operations here <<

  fb->close();

  return 0;
}

Basic template member declaration

basic_filebuf* open ( const char* s, ios_base::openmode mode );

See also